First, this is 44 people, 22 pairs of twins, followed for 8 weeks. This in not enough to be meaningful and the researchers knew this at the start. A sample of 44 people is so small you would only use it for a pilot study to show your study design and get funding.

Second, 8 weeks? That is an insanely short time. Again, pilot study, not real study.

Third, they didn't measure heart disease, they measured LDL cholesterol. This is a proxy marker, not a measure of heart disease. It would be like measuring how many fires a city has by counting firefighters. It doesn't measure how many actual fires there are, just how many resources are available to fight them. What if there is low funding? What if there is an issue with training? What if there is another disaster which is more urgent than the fires? LDL is not a good measure on its own for heart health.

There are lots of other issues but they all boil down to this being bad science. We know what questions should be asked and how to ask them. They chose not to ask questions correctly and get meaningful answers. This is not worth the paper it was printed on and means close to nothing.